Silicone pressure-sensitive adhesives are well known. Generally, they comprise a mixture of a silicone polymer, a tackifier resin, solvents, viscosity stabilizers, and other additives and are cured by thermal and/or catalytic means. Silicone polymers used in these mixtures are gums containing dimethylsiloxy and diphenylsiloxy groups and siloxy groups having a group useful in a crosslinking reaction such as a vinyl or acrylic group. Such adhesives, although useful for many applications, fail for applications necessitating elevated temperatures.
Silicone polymers containing organic groups in addition to oxygen atoms between silicone atoms are well known. These polymers in which the organic group is an arylene group are known as silarylene polymers and those polymers also containing diorganosiloxy groups are known as silarylene-siloxane copolymers. These copolymers can generally be cured by exposure to ionizing radiation or by heating in the presence of well known catalysts. Silarylene-siloxane and siloxane units in the copolymer may have a random distribution as is disclosed in U.S. Pat. Nos. 2,562,000, 3,287,310, 3,332,973, and 4,340,711 or the units may be blocks as is disclosed in U.S. Pat. No. 3,959,403. U.S. Pat. No. 3,444,127 discloses ordered poly(arylenesiloxane) polymers, and U.S. Pat. No. 4,366,323 discloses arylene-siloxanylene polymers.
The silarylene-siloxane copolymers described above can be useful, for example, in high temperature resistant fluids, fibers, coatings, or elastomers.
U.S. Pat. No. 4,534,838 discloses photo-initiating silicones and makes reference to others.
U.S. Pat. No. 4,563,514 discloses radiation curable polysilarylene-polysiloxane copolymers which can be crosslinked in the presence of a suitable cure initiator to provide transparent, self-bonding, dirt repellent, tough, and solvent resistant compositions.
Vinyl substituted silarylene-siloxane copolymers are disclosed in Macromolecules, Vol. 24, No. 16, pages 4503-4509, and 4510 to 4514 (1991). Silarylene-siloxane compositions curable to pressure-sensitive adhesives are not disclosed.
None of the above art or any other art of which the inventor is aware provides a silarylene-siloxane copolymer composition that is curable to an elevated temperature-resistant pressure-sensitive adhesive.